using System;

using System.Text;

using System.Globalization;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        DisplayOutputs("GPS");      

        DisplayOutputs("sk8_r");

        DisplayOutputs("sk_8r");

        DisplayOutputs("love ASP .net");

        DisplayOutputs(".net");

        DisplayOutputs("PeaCe aNd WaR");

        DisplayOutputs("a b c");

        DisplayOutputs("Mr. McGregor"); //The floating uppercase is ignored

        DisplayOutputs("Artis-Payne");

        DisplayOutputs("sing-a-long");

        DisplayOutputs("a.b,c/d[e]f_g{h}i=j!k@l`m~n#o$p%q^r&s(t)u|v?w*x<y>z:a;b");

        DisplayOutputs("7up");

        DisplayOutputs("7up 21st");

        DisplayOutputs("7up __st");

        DisplayOutputs("s8s");

        DisplayOutputs("#YOLO");

        DisplayOutputs("  space start"); //Solution with Regex and TextInfo blows up on this one

    }

​

    private static void DisplayOutputs(string input)

    {

        Console.WriteLine($"--------------Outputs for {input}----------------");

        var textInfo = System.Threading.Thread.CurrentThread.CurrentCulture.TextInfo;

        Console.WriteLine(textInfo.ToTitleCase(input) + " -- Expected Output");

        //SOLUTIONS FROM https://stackoverflow.com/questions/38360688

        Console.WriteLine(input.ToTitleCaseAnswer3() + " --Tokenizer with split and character inspection");     

        Console.WriteLine(input.ToTitleCaseAnswer1() + " --Simple tokenizer with split");

        Console.WriteLine(input.ToTitleCaseAnswer2() + " --Regex and TextInfo");        

        Console.WriteLine("");

    }

}

​

public static class StringHelper

{

    private static readonly CultureInfo _cultureInfo = CultureInfo.InvariantCulture;

    public static string ToTitleCaseAnswer1(this string str)

    {

        var tokens = str.Split(new[]{" "}, StringSplitOptions.RemoveEmptyEntries);

        for (var i = 0; i < tokens.Length; i++)

        {

            var token = tokens[i];

            if (token == token.ToUpper())

                tokens[i] = token;

            else if (token[0] == '-')

                tokens[i] = "-" + token.Substring(1, 2).ToUpper() + token.Substring(2).ToLower();

            else

                tokens[i] = token.Substring(0, 1).ToUpper() + token.Substring(1).ToLower();

        }

​

        return string.Join(" ", tokens);

    }

​

    public static string ToTitleCaseAnswer3(this string str)

    {

        var tokens = str.Split(new[]{" "}, StringSplitOptions.None);

        var stringBuilder = new StringBuilder();

        for (var ti = 0; ti < tokens.Length; ti++)

        {

            var token = tokens[ti];

            if (token == token.ToUpper())

                stringBuilder.Append(token + " ");

            else

            {

                var previousWasSeperator = false;

                var previousWasNumber = false;

                var ignoreNumber = false;

                for (var i = 0; i < token.Length; i++)

                {

                    if (char.IsNumber(token[i]))

                    {

                        stringBuilder.Append(token[i]);

                        previousWasNumber = true;

                    }

                    else if (!char.IsLetter(token[i]))

                    {

                        stringBuilder.Append(token[i]);

                        previousWasSeperator = true;

                    }

                    else if ((previousWasNumber && !ignoreNumber) || previousWasSeperator)

                    {

                        stringBuilder.Append(char.ToUpper(token[i]));

                        previousWasSeperator = false;

                        previousWasNumber = false;

                    }

                    else if (i == 0)

                    {

                        ignoreNumber = true;

                        stringBuilder.Append(char.ToUpper(token[i]));

                    }

                    else

                    {

                        ignoreNumber = true;

                        stringBuilder.Append(char.ToLower(token[i]));

                    }

                }

​

                stringBuilder.Append(" ");

            }

        }

​

        return stringBuilder.ToString().TrimEnd();

    }

​

    public static string ToTitleCaseAnswer2(this string str)

    {

        var tokens = Regex.Split(_cultureInfo.TextInfo.ToLower(str), "([ -])");

        for (var i = 0; i < tokens.Length; i++)

        {

            if (!Regex.IsMatch(tokens[i], "^[ -]$"))

            {

                tokens[i] = $"{_cultureInfo.TextInfo.ToUpper(tokens[i].Substring(0, 1))}{tokens[i].Substring(1)}";

            }

        }

​

        return string.Join("", tokens);

    }

}